Hole-forming tool



July 16, E. DOHERTY ET AL HOLE FORMING TOOL Filed Dec. 22, v1927.

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Patented July. 16,- 1929.

PAT T oi-"Flea.

nzownnn n. nonnn'ry'annaonn' n. mar nes, or. Los ANGELEs, CALIFORNIA.

' HOLE-FORMING TOOL.

Application filed December 22, 1927.' Serial No. 241,788,.

This invention relates to hole-forming tools, and is especially useful in cutting holes through sheet metal, though it may be also employed to advantage on other materials. q i

An object of the invention is to facilitate character employed, for example, in the'construction of outlet boxes and the like used in connection with electrical conduit work in building structures- In constructing a building, the. outlet boxes for switches and the like are set-in place while the building is under construction and, later on, when the conduits that carry the electric wires age placed in position, it is frequently necessary for by partially punched-out discs, which are to provide holes at different places in the outlet boxes than provided in the original construction of said outlet boxes. In the present outlet boxes the holes are provided I only held in place by comparatively narrow strips of metal; In placing the conduits, if

they properly register with said discs, the

discs are knocked out sov that the conduits will enter the holes thus formed in the boxes. If, in placing the conduits, it isimpossible for them to be brought into registration with the discs or holes in the boxes, it becomes necessary to make holes in the outlet boxes while said boxes are in place in the building structure. This is usually more or less difficult because of the comparatively small space for the Workmens tools. It has heretofore been customary to cut the additional holes in' the boxes by first drillinga comparatively small hole'and thenreaming out the hole'to the desired size. The diameter of hole required ranges from an inch to four and one-half inches, and the making ofholes of such sizes with the present tools is very laborious and time-consuming. The operation usually requires about half an hour or more. WVith the present invention, the 0 eration of making a holecan .be' efifecte in about a minute. p

Other objects and advantages will appear in the sub-joined detailed description."

The accompanying drawings illustrate the invention. p

Figure 1 is a side elevation of a hole-forming tool constructed in accordance with the provisions of this invention, the dies being shown separated as though the sheet, in which the hole is to bemade, is in place between said dies.

Figure 2 is an enlargedvertical mid;section of Fig. 1. v

- Figure 3 is an inverted plan view, partly in segtion, from the lineindicated by 3--3, Figure'4 is-a plan view, partly in section, from the line indicated by H, Fig. 2.

Figure 5 is an enlarged fragmental vertical section of the dies in different positions than shown in Fig. 2.

Figure 6 is a perspective view of a piece of metal that has been cut out of a sheet of material by operation of the inventionl Referring to the drawings, there are provided male and" female dies 7, 8. A suitable means is provided for forcing the dies 7, 8 toward one another, and such means in this instance comprises a threaded member 9 that extends through holes 10, 11 in the respective dies 7, 8. Threaded'onto the member 9 are nuts 12. one of which bears against the outer 'face of the die 7 and the other against the outer face of the die 8. The particular means just described for forcing the dies 7,

8 together is of advantage as they enable the tool to be operated in a comparatively small space, as is generally necessary in the making of holes in outlet boxes after said outlet.

boxes are in place in building structures. A suitable wrench, not shown, will be applied to either of the nuts to relatively move the dies toward one another or to unscrew the nuts so that the member 9 can be removed from the dies'to permit of them being removed from the work after the hole has been formed.

The die 7 is provided with a cutting edge is preferable to have three or four such sections, and, in this instance, four are shown. The sections 16 constitute tooth-like prominences. The greater the number of cutting edge sections 16, the greater may be the pitch or angle of the cutting edge with any given depth of cutting edge. The greater the pitch or angle of the cutting edge to the sheet being cut, the greater the case with which the cutting edge cuts through the material. The cutting edge sectlons are helical, or in the form of a screw, and each defines at one end a point 14 that first penetrates the material in which the hole is to be made. Thus the cutting edge terminates at one end in a point and the oppos te end of said cutting edge extends to a different level adjacent to said point.

The die 8 is provided with a recess 15 to receive the die 7 and, preferabl the recess 15 expands inwardly so that a er the tool has been operated to make a hole the punching out from said hole Wlll loosely fit the bottom of the recess, in order that said punching can more readily be extracted from the recess 15 by pressing the punching at the margin on one side so as to force the margin at the other side out of the recess. Because of the peculiar shape of the punching, indicated at A, Fig. 6, extractlon of the "punching from the recess 15 1s very easily accomplished. The rim of the recess 15 defines a cutting edge 151, which is em phasized by beveling oflt' of the end of the recess wall 152.

Referring again to the cutting edge 13, said cutting edge is formed by bevehng, thickness-wise, the tooth-like sections 16. The sections 16, preferably, are thicker at their bases than at their tips, for the sake of strength.

The tool above described operates as follows:

A comparatively small hole B will first be drilled in the sheet C, at the axis or" the larger hole that is to be formed. Then the dies 7 8 will be placed on opposite sides of the sheet C, as shown in Fig. 2, with their holes 10, 11 aligned with the hole B. Then the member 9 will be passed through the holes 10, 11, B and the loose nut 12 will be secured onto the member 9. The parts will then be in the positions shown in Fig. 2.

A wrench, preferably a ratchet wrench, will then be applied to either of the nuts 12, and operated to screw said nut toward the other nut, thus forcing the dies 7, 8

toward one another. This causes the points 14 to penetrate the sheet C, as clearly shown in Fig. 5, and immediately a shearing action is produced by the cuttmg edge 13 so as to shear the material between the points 14. The angle and length of the cutting edge 13 will be sufliciently great so that by the time the bases of the members 16 pass through the material the hole will be out. In the cutting operation, the blank A may be more or less deformed at its margins, as clearly shown in Fig. 6, due to the fact that the pressure of the cutting edge 13 bends the material of the sheet downwardly as the cutting edge proceeds.

edges comprising a series of beveled elements, each of which beveled elements gradually rises and abruptly terminates at a point, and means to produce relative non-rotative movementof the dies toward each other whereby to effect a shearing action on the work.

2. A hole forming tool comprising dies provided with co-operating cutting edges extending about a center, one of said cutting edges comprising a series of beveled elements, each of said beveled elements having a surface which gradually rises and abruptly terminates at a point, apertures extending through both of said dies and means extending through said apertures to produce relative non-rotative movement'of the dies toward each other whereby to eltect a shearing action on the work.

A hole forming tool comprising dies,- said dies having apertures, a threaded member extending through said apertures, said dies having means providing co-operating cutting edges extending around said apertures, one of said cutting edges comprising a plurality of beveled elements, each of which gradually rises and abruptly terminates at a point, and means on said threaded member to produce relative non-rotative movement of the dies toward each other whereby to effect a shearing action on the work.

Signed at Los Angeles, California, this 15th day of December, 1927.

EDWARD M. DOHERTY.

JOHN H. JEFFRIES. 

